I’m working on implementing email verification for our newsletter signup process. We want to validate email addresses using Mailgun’s validation API right when people sign up, before storing their information in our system.
I have two main questions about this approach:
First, how reliable is Mailgun’s email validation service? Are there cases where it might incorrectly mark a valid email address as invalid? I’m worried about rejecting legitimate subscribers due to validation errors.
Second, if we end up with an email address in our database that was previously flagged as questionable, what happens when we try to send messages to it? Does Mailgun perform additional checks during the actual sending process, or will it attempt delivery regardless of previous validation results?
Has anyone experienced issues with Mailgun’s validation being too strict or missing valid addresses? I want to make sure we’re not losing potential subscribers while still maintaining good list hygiene.
I’ve been using Mailgun’s validation service for about two years now and can share some practical insights. The accuracy is generally solid, but you’re right to be cautious about false positives. I’ve noticed it sometimes flags legitimate corporate emails as risky, particularly from smaller companies with stricter mail server configurations. Regarding your second question, Mailgun doesn’t automatically block emails during sending based on previous validation scores. The validation API and sending service operate independently. However, emails to addresses that were flagged as invalid will likely bounce anyway, which affects your sender reputation over time. My approach has been to use validation scores as guidance rather than hard rules. Instead of completely rejecting questionable addresses, I implemented a two-tier system where risky addresses get flagged for manual review or receive a confirmation email before being added to active campaigns. This has helped maintain list quality while avoiding the loss of legitimate subscribers who might have been incorrectly flagged.
Just went through this exact implementation last month and learned a few things the hard way. Mailgun’s validation definitely has quirks - we saw false positives with some educational domains and international addresses that were perfectly valid. The service tends to be more conservative which can hurt your conversion rates if you auto-reject everything flagged as risky. What caught me off guard was discovering that validation results don’t influence the actual delivery attempts. Mailgun will happily try sending to addresses previously marked as questionable, and those bounces still count against your reputation metrics. We ended up implementing a hybrid approach where we validate at signup but only hard-block the obviously invalid ones while sending confirmation emails to the questionable addresses. This way legitimate users can still subscribe even if the validation service was overly cautious about their domain.
been running mailgun validation for 6 months now and honestly its pretty good but not perfect. had some issues with gmail aliases getting marked as invalid when they were totally fine. the validation doesnt stop actual sending tho - if you have a “risky” email in your db mailgun will still try to deliver it when you send campaigns.